Optical navigation devices use a light source to illuminate a navigation surface to provide digital images for computing motion. For example, a finger on a surface may be imaged to generate a navigation signal. Tactile switches may be implemented in conjunction with optical navigation devices. For example, an optical mouse may include one or more tactile switches such as a left click button and a right click button that allow a user to make a selection by clicking on the left and/or right click button. The conventional implementation of an optical navigation device and a tactile switch separates the operation of the optical navigation device from that of the tactile switch. For example, on the optical mouse, the optical navigation device is typically on the bottom of the optical mouse where the mouse is placed on a flat surface. As the mouse is moved, the optical navigation device tracks movement of the mouse relative to the flat surface. The tactile switch, on the other hand, is placed on the top and/or the side of the mouse. Hence, the operation of the optical navigation device occurs independent of the tactile switch, and vice versa.
However, as the size of navigation devices is reduced, the optical elements and sensors for detecting the optical navigation input are allotted less internal space for assembly and operation. For example, the inclusion of a user input interface on a modern cell phone and/or handheld computing device comes at a premium. Implementing a tactile switch in conjunction with an optical navigation device on a handheld computing device would include one space on the surface of the handheld computing device for the optical navigation device as well as another space on the surface of the handheld computing device for the tactile switch. Including two or more user input interfaces on the handheld computing device consumes valuable surface space on the handheld computing device that could be used to increase other functions of the handheld computing device including screen size, processing power, memory space, and/or battery capacity.